Yarn traversing drums for textile winders having helical yarn guiding grooves are generally old and well known. Such drums support and frictionally drive packages being wound thereon to form cross-wound yarn packages. Automatic winders are capable of operating at winding speeds of as much as 1,500 meters per minute. At these high winding speeds, there is a risk of the guided yarn escaping from the traversing grooves, particularly at the groove intersections and most particularly at the central intersection where the yarn has a tendency to resist being guided away from the central location at which the yarn is fed to the drum. Obviously, when a yarn escapes from a groove or shifts from one groove to the other at an intersection, winding errors occur that can result in an imperfect cross-wound package, causing problems in subsequent processes in which the yarn is unwound from the package for further processing.
Various attempts have been made to improve the reliability of yarn traversing guiding by modifications of the configuration of the grooves. For example, German Patent Disclosure DE 40 10 470 A1 discloses grooves having a lobe-shaped cross-section for the purpose of retaining the yarn in the groove. However, this groove configuration does not significantly improve the yarn retention at groove intersections, particularly at the central intersection where the yarn tends to be close to the surface of the drum and tends to maintain a central position, resisting the outward guiding by the grooves.
The problem is less at groove intersections that are spaced from the center of the drum as relatively shallow groove sections can be utilized in guiding the yarn in the direction toward the center, which direction does not change tension at outwardly spaced intersections, and the deep groove sections reliably guiding the yarn traversing in the direction away from the center.
The problem is significantly more difficult at the central intersection of the grooves where there is little problem with a deep groove section in traversing in one direction, but there is a significant problem when the yarn is being traversed in the opposite direction in a shallower groove section. To alleviate the problem somewhat, relatively large yarn-capturing pockets are formed in the shallower groove, but even with such configurations there is a tendency at current conventional high winding speeds for the yarn to escape from the yarn-capturing pockets and be engaged in the opposite deep groove to be traversed back in the wrong direction.